To travel happily with only a carry on and a personal bag, one has to accept the following:
Laundry will have to be done frequently. We do ours by hand and it only takes 20 or so minutes a day. If you don’t have experience doing hand washing while traveling, let me know and I'll let you in on a few tricks that should make things easier.
You will wear the same outfit more than once. Maybe two or three times each. But, you must not worry about what others may think. If you are with a group, you'll see them in the same outfits multiple times. If traveling solo, or with just a partner, who will know. Then too, they don't pay your bills, so why worry.
Don't take a hair dryer. Every place we’ve stayed in Europe in the past has had one in the room. Or you can borrow one from the front desk. Worst case scenario, you buy a small cheap one there.
Some general thoughts:
Take only black, white, and grey clothing that can be mixed and matched. You can add a splash of color with a scarf, belt, tee, or tank. Take things that are light weight, wrinkle free, and will dry quickly. Several sources are Magellan's, Travel Smith, and Chico's. All have web sites and Chico's has regular stores. Chico's is really great.
If you take a lot of meds, get an extra label from the druggist, put it on a freezer zip lock, put the pills in the baggie. Saves a ton of space and weight. Just be sure take the data sheet with you to show what it is and that it is for you.
Take very little jewelry. One or two necklaces and ear pieces at the most. Take only two purses. Your regular day bag will do for daytime. If you feel the need for another then a small clutch for evening.
Do not take a lap top or tablet. It will take up space and add weight. Check email with a smart phone.
Before I forget, if you are traveling with someone, always put half of your stuff is their bag and half of their stuff in your bag. Carry on bags are sometimes gate checked no matter what the size / weight. If one of the bags goes on its own vacation, both will still be able to get by.
Clothing:
Three under shirts – two regular and one tank top – wear one and pack two.
Five underwear -- wear one and pack four.
Three bras -- wear one and pack two.
Five pairs of socks – wear one and pack four.
Two pairs of shoes – wear one and pack one.
Three pairs of pants – wear one and pack two.
Three shirts or blouses – wear one and pack two
One jacket and one belt – both to be worn in route.
One vest, one sun hat, and one light sweater – all to be packed.
Rain coat to be packed.
This is a bare bones packing list. You might be able to add another shirt or pair of pants – just depends on how much space is taken up with cosmetics, phone chargers, guide books, and misc. I also carry a RS Veloce Shoulder Bag as a personal item. It will hold lots of odds and ends. And at least one change of underwear.
This list isn’t perfect for everyone but it works well for me. I also use a combination of packing cubes, folders, and tubes to organize things and aid in the placement of the various items. One of the keys to being able to travel for a long period with only a carryon is experimenting with the packing and seeing what does and doesn’t fit / work.
Hope this helps. Let me know if you need additional specifics.